Re: [Plplot-devel] Circle support

[Alan W. I. <ir...@be...>]

On 2009-05-27 09:36+0200 Robert Pollak wrote:

> Alan W. Irwin schrieb:
> [...]
>> Clearly, in the case of example 32 a circular symbol was meant.
>> examples/python/test_circle.py contains a number non-unicode and unicode
>> ways of generating such symbols.  Example 1 and Example 6 show additional
>> methods of generating circular symbols.  I suggest example 32 be simplified
>> to use one of those methods rather than using the local "plcircle" function
>> that is currently implemented in x32c.c to duplicate that already-existing
>> PLplot core functionality for generating circular symbols.
>
> I agree. Here is the patch to use plpoin as in examples 1 and 6.

Hi Robert:

Thanks, for the patch.  I have applied it with a change to use a larger
circle rather than the smallest one (revision 10007).  For my eyes this
changes the outliers from an annoying dot on the plot to something that is
clearly visible.

> What gets lost, though, is the demonstration of how to get the axis
> ratio for drawing custom symbols.

This idea should obviously be reserved for geometrical figures (as opposed
to pure symbols which by definition always appear the same regardless of
world coordinates or aspect ratio).  Assuming Hez's use case for his
suggested new API is for a geometrical arc attached to world coordinates as
opposed to just a symbol, a new example that uses that new API might be a
good opportunity to demonstrate the axis ratio technique just removed from
example 32.

The rest of this post is directed to Andrew.

Hi Andrew:

The existing example 22 might be another possibility for demonstrating the
axis ratio technique, but in that case I think there is also a possibility
to moving to pure symbols which leads to a further question.

What do you think of the idea of changing plvect to use unicode fonts
internally to draw the required arrows?  See example 23 for a large
selection of such arrow possibilities in the unicode world.  Of course, for
devices that are not unicode aware you would internally fall back to the
present drawn arrows (suitably scaled so the results are independent of
world coordinates and aspect ratio).  Or you could ignore unicode altogether
and use the suggested fallback for all devices regardless of whether they
are unicode or not.

It appears from your previous post in this thread that axis scaling is
required for certain uses of the current plvect.  That step should no longer
be necessary if you changed plvect to generate pure symbol arrows as
outlined above.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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